This invention relates to systems for movement of temperature-controlled air, and more particularly to duct systems for movement of air inside temperature-controlled cargo containers.
Trucks, trains and other carriers hauling temperature-controlled cargo containers transport perishable products around the country every day. Refrigeration of a temperature-controlled cargo container involves distributing temperature-controlled air, typically cool or cold air, within the enclosure of the container. A refrigeration unit is used to adjust and control the temperature of the air drawn from the outside environment or from inside the enclosure. This temperature-controlled air is then distributed throughout the enclosure.
Ordinarily only a single refrigeration unit is employed with a single cargo container. The temperature-controlled air ordinarily must be directed from the refrigeration unit to other locations inside the enclosure. Such direction promotes proper circulation of air, which helps create and maintain the desired uniform temperature inside the enclosure.
In the context of a trailer or a railroad car, the cargo container is usually in the shape of an elongated box, with a refrigeration unit mounted at one end. To move temperature-controlled air around the container, a system of channels may be employed to conduct the temperature-controlled air to the end of the container farthest from the refrigeration unit. Other channels can direct the air to the middle sections of the container and around the sides. The channels are often placed above the cargo and distribute the air near the ceiling of the container. Distribution of cool air near the ceiling will enhance air circulation because cooler air is more dense than warmer air and tends to sink to the floor.
Cloth or canvas chutes have been employed in the past to direct airflow. Cloth and canvas chutes are relatively inexpensive, but they suffer from several disadvantages. First, if a chute is damaged, the entire chute must ordinarily be replaced. Even if the damage is repairable, the entire chute must ordinarily be removed from the temperature-controlled cargo container for repair. Second, chutes are difficult to clean, and because refrigerated cargo often includes food products, cleanliness is important. Third, chutes are not easily adjustable to direct air to particular areas within the container, such as the sides of the container. Fourth, chutes tend to wrinkle and flap, restricting air flow and hampering air distribution. Fifth, it is difficult and time-consuming for one person to install a chute, in part because the chute must be installed with a proper amount of sag along its length to create an airflow channel.
The invention provides a modular duct system for conducting air in a temperature-controlled cargo container. Temperature-controlled air produced and propelled by a refrigeration unit is conducted along the modular duct system by one or more duct sections and a transition section that conducts air from the refrigeration unit to the duct sections. An end section may be coupled to the duct sections. Individually adjustable discharge openings allow the air to be discharged to the sides and the rear of the temperature-controlled cargo container. The invention further provides a method for directing temperature-controlled air in a temperature-controlled cargo container using a modular duct system installed along the ceiling of the temperature-controlled cargo container. The invention also provides a method of installation of such a modular duct system.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.